It is found, from an experiment on a conventional Pushlet instant messaging (IM) server, that the speed at which client devices may receive messages becomes slower when a pushing period of the messages ranges between 300 ms to 1 s in the conventional Pushlet IM server. As a result, pending messages in an event queue that are to be pushed to the client devices may pile up since the conventional Pushlet IM server is configured to use a stack method for pushing messages one at a time, increasing load of the conventional Pushlet IM server and resulting in failure to instantly push messages to the client devices.
Moreover, the conventional Pushlet IM server communicates with the client devices based on hypertext transfer protocol (HTTP). Accordingly, the conventional Pushlet IM server cannot communicate with the client devices under other types of communication protocols, such as simple object access protocol (SOAP) and extensible markup language (XML). In other words, applicable fields of the conventional Pushlet IM server are limited.